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Is that not saying that the FSDs are not engineered to work correctly with non-sport springs? Meaning sure they can bolt in there but will not ride/handle correctly because the FSD is designed to work with a "tighter" spring.

I think that css is being pedantic. While the points raised may be applicable if you are wanting to build a car that will run the 'Ring with the shortest possible lap time, in the 'real world', the Koni FSDs will work just fine with Sport and non-Sport E90 suspensions.

Yup. On the front, the strut/damper has a 'hat' (don't know what the technical term is for the flange/whatever) that holds the spring.

Is the rear the same way? I seem to recall my old Honda and Galant were both this way, so you ended up disassembling everything and from a labor stand point it would take no more time to do springs when doing the struts/shocks/whatevers.

I think that css is being pedantic. While the points raised may be applicable if you are wanting to build a car that will run the 'Ring with the shortest possible lap time, in the 'real world', the Koni FSDs will work just fine with Sport and non-Sport E90 suspensions.

Not at all.... BMW engineers spend countless hours designing the suspension systems for these cars and that includes pairing the right springs and shocks together. Shoot, they will even put a slightly different set-up on a car depending on the options (added weight).

Why on earth anyone would think they can just slap any old shock on their car without the potential of negatively impacting the suspension geometry is beyond me.

I get that BMW engineers a complete package but what I do not quite get is how can we say for certain what Koni engineers their parts for in regards to spring selection.

You're right, but they can't engineer a single shock for 2 different springs, it just doesn't work that way. My best guess is they tried to compromise which means the shocks will not necessarily be excellent for any one application. In that case, why not stick with OEM? At least you know they are designed for your car/springs.

Not at all.... BMW engineers spend countless hours designing the suspension systems for these cars and that includes pairing the right springs and shocks together. Shoot, they will even put a slightly different set-up on a car depending on the options (added weight).

Why on earth anyone would think they can just slap any old shock on their car without the potential of negatively impacting the suspension geometry is beyond me.

We will just have to agree to disagree. In the mean-time, everyone who has installed a set of FSDs on their E9X (equipped with both Sport and non-Sport package) cars in the non-Diesel universe are raving about the improvements they are experiencing in the 'real world'. There are a number of threads that back up that circumstance.

We will just have to agree to disagree. In the mean-time, everyone who has installed a set of FSDs on their E9X (equipped with both Sport and non-Sport package) cars in the non-Diesel universe are raving about the improvements they are experiencing in the 'real world'. There are a number of threads that back up that circumstance.

Look I am not knocking your Koni's they are good shocks, shoot I considered them myself when I was in the process of figuring out what I was going to do with my suspension system. I've seen just about every review out there - I am very active on the other board.

Most people that swap to just Koni shocks (no springs) are doing so because their original shocks are shot or are approaching the end of their useful life so they are looking for a replacement alternative to stock shocks. The others who installed Koni did so early in the process in an effort to actually try to improve their car's handling characteristics and thus paired them with a tighter more performance oriented spring.

That being said, for the most part reviews are favorable and certainly one's perception is reality. However, I would not say for those that have changed out just their stock shocks that some daily driver's impression is any credible review of how well the Koni shocks improved or negatively impacted one's suspension geometry.

The real question here for Axel is; What are you trying to accomplish by swaping out relatively new and perfectly good OEM Bilstein shocks for Koni shocks? If it's an improvement in handling you are after, you are only looking at 1/2 of the equation and anyone that tells you otherwise does not know what they are talking about.

Look at either a coilover or spring and shock kit that are engineered to work together

Axel take a look at this kit, it is awesome combo if you want to maintan the daily driveability of your car while at the same time improving the handling and lowering the stance a bit. Best of all it is designed/engineered by the suspension guru's at BMW.

Thanks Chris, as I stated before I used the FSDs on my 02 MCS which had the sport suspension and after the swap the car handle FAR better than stock yes, STOCK ( I left the sport springs on, just in case anyone asks me about them), to put it this way I let 3 different individuals drive MCS and two inmediately purchased the FSDs and believe or not they were STOCK MC not MCS, the third person whom happens to be JP Performance out of Puerto Rico the owner Jean Paul had an MCS an after he test drove my car he was upset he had sold the it 2 weeks earlier. He loved the MCS he had to sell it cause his back was paying the price. Mind you this guy deals with Porsche and other high end vehicles and he is the offical M7tuning.com installer and dealer, also Peter Hovarth from M7 test drove the car and was amazed in how the car drove and handle. All that said I firmly believe my vehicle will ride better and handle these freaking rodes of my Island. I CANNOT say wether it will work with my 335d since I have NOT heard from any other D about this issue. I will keep all of you posted as I have with intake, ECU etc etc. Gracias for inquiring.

BTW @Chris the purpose for making changes is because I have ventured to anohter place with my 335d and my defunct 02 MCS and I attest for these products, so far RENNtech has not let me down and we'll see if FSDs can come up to the plate. Will keep u all posted

Thanks Chris, as I stated before I used the FSDs on my 02 MCS which had the sport suspension and after the swap the car handle FAR better than stock yes, STOCK ( I left the sport springs on, just in case anyone asks me about them), to put it this way I let 3 different individuals drive MCS and two inmediately purchased the FSDs and believe or not they were STOCK MC not MCS, the third person whom happens to be JP Performance out of Puerto Rico the owner Jean Paul had an MCS an after he test drove my car he was upset he had sold the it 2 weeks earlier. He loved the MCS he had to sell it cause his back was paying the price. Mind you this guy deals with Porsche and other high end vehicles and he is the offical M7tuning.com installer and dealer, also Peter Hovarth from M7 test drove the car and was amazed in how the car drove and handle. All that said I firmly believe my vehicle will ride better and handle these freaking rodes of my Island. I CANNOT say wether it will work with my 335d since I have NOT heard from any other D about this issue. I will keep all of you posted as I have with intake, ECU etc etc. Gracias for inquiring.

You must have ignored my earlier posts. Starting with post 15 I have been commenting about my experience with FSDs on my d. There are other Festers with gasser E9X cars that have swapped out the stock shocks for FSDs and are raving about the improvement.

@anE934fun, sorry about this and my apologies. You posted right after I did on #14. How much do you enjoy your FSDs i am planning in leaving the Non-sport springs

As BF member Captain Audio posted in one of the threads about FSDs - the FSDs are what BMW should have included for shocks when the cars left the factory. My first experience with FSDs was on a 2005 MCS. The ride was killing my back. After the FSDs, everything was fine. Everyone I know who have swapped out the oem shocks for FSDs has been amazed at the result. Good luck on your swap.

Another data point - hard shocks from the factory contributed to the strut tower mushrooming issue on the gen 1 Minis. People who purchased their Mini in the same group buy as I did, but didn't swap out the shocks, experienced mushrooming. But my car with FSDs was free of mushrooming....

Very true about this the only other way to prevent mushrooming was to buy from M7tuning their strut plate which is very good in preventing this, I had them on my car and NEVER had any more problems with mushrooming and or breaking of rubber strut mount which costs arounf $70 a pair by now and not installed

Ok amigos the FSDs are in place but not able to drive the damn car since Im going to RENNtech to get it reflash since I had the EGR issue resolved by BMW. I will keep you posted as to the ride qualities, BTW amigos! when i installed my 1st of FSDs I owned an 02 MCS, I LEFT the OEM springs which BTW were SPORT springs and the car HANDLED and DROVE better for all these years stop!! making mathematical issues about this just do as I did BUY whatever pleases you , damn can we just get along here !!! LOL

Axel proceed with caution when considering changing out shocks without addressing springs. I would suggest replacing your springs at the same time with a spring with a higher spring rate e.g. either zsp springs, EPK's or similar. The shock/spring system is engineered to work in concert. Shocks are designed to manage the spring rates they are paired with. A shock that cannot handle the rebound and or dampening of a stiff spring will result in a bouncy ride and vice versa. I can't tell you how many people I have read about that only did one without the other only to end up paying for the install all over again to have matched springs installed. Just my $.02

Have you considered the BMW Performance suspension kit (springs and shocks together)?

I completely agree with CSSNMS. My D was a base and I replaced with the BMW Performance Suspension about a year ago and couldn't be happier. I nosed about the forums heavily before deciding to go this route and while the Konis got a lot of love, there seemed to be a fair bit of consent that spring choice would have a major impact on the total ride quality. Since the BMW Performance Suspension comprised - and maybe still does - of a stiffer front sway bar, f and r struts, and f and r springs, And a bunch of bits and bobs for a complete install kit, all matched by BMW testing, I reasoned that this would be the safest choice. The kit was less than 1500 at the time and cost me another 500 to have a very reputable local tuning shop install. Best 2k I ever spent. This combo magically smoothened the ride, improved lateral handling, decreased body roll, and vastly improved cornering.

@tonyspumoni good choice but if you live in Puerto Rico the sport suspension is NOT a wise idea, having come from a 02 MCS with sport suspension and then added the FSDs the car drove EXCELLENT with the FSDs but the roads here were no mercy to it. I decided to stay with the NON sport springs on my 335d and trust me I drove the car approximately 100 miles yesterday at speeds of 75-120 mph and the car was stout and the rate of the spring with the FSDs were MARVELOUS, my girlfriend who does not know nothing but put gas in her car LOL, noticed the car drove very lightly and couldnt feel the bumps and potholes at all compared to the previous OEM schocks.

I drove around the mountains and may curves and barely a tilt compared to the OEMs were a dive and a thump on unpaved roads were a given!!

The only down side is the car lifted approx 1 inch and my LCI lights decided to face downwards i believe due to the new height , I will go to the dealer to fix this.

I am VERY happy with my setup and handling of my car, if I lived in the states then I would consider the sport springs but down here in Puerto Rico, NAAHH!!!!

Loving my FSD's for now!!! My friend owns a 330 and he drove my car and he couldnt believe how well it handled the road, he said the car felt great, plus he told me that RENNtech woke up the monster!! with it latest flash!!